High-frequency hair waver



y 24, 1951 G. BRIGGS 2,561,609

HIGH-FREQUENCY HAIR WAVER Filed March 5, 1946 2 Sheets-Sheet l Gab f BY 5 uvau ra.

July 24., 1951 G. BRIGGS HIGH-FREQUENCY HAIR WAVER 2 Sheets-Sheet 2 Filed March 5, 1946 run/591ml? a mfawww Patented July 24, 1951 HIGH-FREQUENCY HAIR WAVER George Briggs, London, England Application March 5, 1946, Serial No. 652,042 In Great Britain March 15, 1945 3 Claims.

This invention relates to improvements in the waving of hair, more particularly the so-called permanent waving of human hair, and has for its chief object to provide a new method. of carrying out the said process and also apparatus for carrying out the said new method.

As heretofore proposed, there have been two main methods of permanently waving human hair, i. e., the rising heat and falling heat processes. In many respects the rising heat process has advantages, particularly in the result produced, but it has the disadvantage that it has involved the person whose hair is being waved being tied to the waving apparatus by a number of wires for a considerable period. In other words, the head of that person is connected to the apparatus by flexible electric conductors leading to the heating elements. This has, in many cases, a detrimental psychological effect on the person in question. This is, of course, not present in the falling heat system of permanent waiving but, as stated above, this system is not in general favoured.

In carrying out the present invention, the curlers on which the tresses of hair are wound are themselves made of, or associated with elements made of, a metal into which electric currents may be induced from a non-integral high frequency source'so that the necessary heat may be quickly generated in or about the said curler to carry out the waving process.

In order that this invention may be the more clearly understood and readily carried into eifect, I will proceed to describe the same with reference to the accompanying drawings, in which:

Figure 1 illustrates diagrammatically the basic electrical circuit of the preferred form of apparatus for carrying out the present invention.

Figure 2 is a perspective view of a curler designed to prevent the occurrence of hot-spots and to secure the even heating of the tress of hair wound thereon, and

Figure 3 is a transverse section through the same.

Figure 4 is a transverse section through a wound curler provided with an outer sheath of Mumetal or the like to ensure that the tress of hair is heated both from the inside and the outside.

Figure 5 is a diagrammatic view illustrating the application of the present invention to the tipto-root or Croquignole system of hair waving.

Figures 6 and 7 are respectively a perspective view-of and a transverse section through a further form of curler that may advantageously be used in carrying out the present invention.

Figure 8 is the circuit diagram of a suitable protective system for use in the apparatus according to the present invention, and

Figure 9 illustrates a modification of such a protective system.

In carrying out the present invention, the curlers on which the tresses of hair are wound are themselves made of, or associated with elements made of, a metal into which electric currents may be induced from a non-integral high frequency source so that the necessary heat may be quickly generated in or about the curler to carry out the waving process.

Mumetal has been found to be the most suitable material to employ, but it must be clearly understood that the present invention is not limited to the use of this material since other metals, for example that sold under the trade name Permalloy, may be employed.

The tresses of hair on the curlers are treated individually rather than all together since this enables the necessary apparatus to be made smaller and simpler and, furthermore, materially reduces the power required to heat up the curlers. The preferred apparatus thus comprises (referring to Figure l of the accompanying drawings) basically a H. F. generator II of a suitable form fed from the mains I2. The most satisfactory frequency has been found to be 400 kcs./sec., but this may be varied without departing from the scope of the present invention. The output I3 from the H. F. generator I I is coupled to a coil I4 which in turn is connected to the work coil I5 through a condenser I6. The coil I4 is adjustable as shown for tuning purposes.

The work coil I5 is preferably carried in the barrel of a gun (not shown) which can be slipped over the Mumetal curlers I I on which the tresses of hair l8 are wound one by one. The very intense field which can be generated by the coil I5 in the barrel of the gun enables the curler I1 to be brought up to the required heat very quickly (in a matter of seconds as distinct from minutes). Thus the overall time required to treat the whole head of hair by dealing with the wound curlers one after the other is not increased out of all proportion as would at first sight appear to be the case. In fact the time is reduced as compared with previously proposed systems.

The fact that the heat can be generated so quickly leads, however, to its own difficulties. The field is, of course, most intense at the centre of the barrel of the gun carrying the coil I5 and the speed with which the curler I1 is raised in temperature leads to the formation of a hotspot between the ends of the curler. The temperature gradient from the centre to the ends of the curler is so reat, particularly if the curler be made of Mumetal, that if the curler be heated for sufficiently long to raise the ends of the curler to the desired temperature the middle gets too hot and so burns the tress of hair at this point whilst, if heating be stopped when the centre of the curler has reached the desired temperature, the ends of the curler have not attained a sufficient temperature adequately to bake the tress of hair at these points.

With a view to overcoming this disadvantage, a curler of the form shown in Figures 2 and 3 of the accompanying drawings may be employed. In this case, the curler base I! of Mumetal, or other material into which heating currents can be induced, is surrounded by a split sheath 20 of non-magnetic metal of good heat conducting qualities, such as aluminium.

The outer sheath 2!] of aluminium or the like should be in good physical contact with the core I! so that it may, by reason of its good heat conducting qualities, attain the same, or substantially the same, temperature throughout the whole of its length even within the short time that the composite curler is subjected to the heating current.

The object of splitting the sheath 20 is to enable the heating current to reach the core l1. If the sheath 20 were not split it would act as a shield and prevent the core heating up. It is not necessary that the sheath should not extend completely around the core. The edges of the sheath may, if desired, overlap provided they are electrically insulated from one another.

Such an arrangement of curler has been found to overcome the hot spot difficulties above referred to and to give a satisfactory baking of the tress of hair wound over the outer sheath.

With the system of hair waving according to the present invention it would be appreciated that in controdistinction to the usual method of permanently waving hair the heat is generated in, and applied to, the centre of the wound tress of hair. This tends to give a hard curl at the. centre of the wound tress of hair and a soft curl at the outside which may, in some cases, be considered to be a disadvantage.

In order to overcome this disadvantage, after the tress of hair curler H, the same is surrounded by a split sleeve 30 of Mumetal, or other suitable metal into which high frequency heating currents may be induced, as shown in Figure 4.

The outer sleeve 30 must be split in order to enable the high frequency heating current to reach the centre curler I! and to heat the same. If the sleeve 30 were not split it is true that it would be itself heated up but it would act as a shield to the centre curler and would prevent the same being heated up. As it is, with such an arrangement, the wound tress of hair is heated, or baked, both on the inside and the outside and a very effective curl is obtained.

It is not necessary that the sleeve 30 should not extend completely around the centre curler I l. The edges of the sleeve may, if desired, overlap provided they are electrically insulated from one another. Thus, for example, the sleeve may be formed from a piece of Mumetal foil or thin sheet which is wrapped around the wound tress of hair, one side of the foil or the like being provided with a layer of absorbent lint or other insulating material which serves not only electrically to insulate the overlapping l8 has been wound on the parts of the sleeve but also as a carrier for any reagents it is desired to apply to the hair during the baking process.

The gun form of carrier for the work coil l5 will be found to be quite satisfactory for a hair waving system where the tresses of hair are wound on to the curlers from root-to-tip. Where, however, the tresses of hair are wound on to the curlers from point-to-root, such apparatus is not practicable since the root of a tress of hair lies at the centre of a curler instead of one end.

Viewed purely from the theoretical aspect of heating, the curler could be of substantially the same shape as that heretofore used for pointto-root winding and be made of Mumetal (or another suitable metal). The apparatus would be provided with two small current carrying or work coils 40, 4| (Figure 5) which can be brought into position about the free ends of the curler. In such a case, however, high frequency heating currents would be induced only into the ends of the curler. Very sharp, temperature gradients would be set up from the ends of the curler to the centre, with the result that lon before the centre of the curler had been heated sufficiently to bake the hair at this point the edges of the coil-of hair on the curler would be burnt. What is required is some means of ensuring that the curler is heated evenly, or substantially evenly, throughout the whole of its length.

For the point-to-root system of hairv waving, therefore, the curler is not in the form of a rod of Mumetal or the like but, as shown in Figure 5, comprises a split sleeve 5|] of aluminium or other non-magnetic metal of substantially the same shape as that used in the point-to-root method of waving the hair, and is provided internally with a number of wires 5| of soft iron, Mumetal, or other magnetic material, the wires being closely packed and in good contact with the curler at its centre or point of smallest cross-section 500. and being spaced apart and preferably out of contact with the curler at the ends about which the heating coils are to be disposed. Plugs 52 of soft iron or the'like may be provided about the ends of the wires, theseplugs being spaced from the ends of the curler so as not to heat the same by direct conduction.

The split in the outer aluminium or like sleeve will ensure that the heating currents are induced into the wires and by suitably choosing the number of wires and arranging their packing it can beensured that the centre of the curler will be heated up by conduction at the samerateas the other parts of the curler which are heated partially by conduction and partially by radiation, the ends of the outer sleeve within the heatin coils preferably being heated by radilation from the plugs only.

In place of the wires 5| a solid core may be employed.

In the previously proposed processes of waving hair, there is no chance of the curler burning the tress of hair and there is, therefore, no objection to the tress of hair being wound directly on to the. curler. With the system according to the present invention it is usually the curler which is heated and there is a risk of the tress of hair being burnt, particularly in view of thegreat speed at which the curler rises in temperature.

In order to overcome this possible disadvantage, the curler. I! may be providedwith a sleeve or covering 55 which keeps the hair out of contact with the metal of the curler.

The sleeve 55 may be made of fabric and be slipped over the curler or, alternatively, the covering may be provided by a strip of asbestos braid or the like which is Wound about the curler.

In all cases the sleeve or covering is preferably porous so that it may serve as a carrier for the reagents used in treating the hair and, if desired, sleeves or coverings of different thicknesses may be provided so that different amounts of reagents may be used to vary the time of steaming of the tresses of hair.

As above mentioned, the curlers are heated up very rapidly, particularly when a gun is employed, and so steam is generated very rapidly. In order to avoid all chance of this steam rushing out of the front end of the barrel of the gun and burning the scalp of the person whose hair is being wound each tress of hair may be surrounded by a rubber or other resilient sleeve which at one end is adapted to grip the tress of hair tightly at the roots and at the other end is adapted to take over a ridge on the forward end of the gun, thereby preventing the egress of steam from the forward end of the barrel. I

If desired, the resilient sleeve may be provided with a rubber or like pad adapted to rest on the scalp. As an alternative, the resilient sleeve may be carried by the forward end of the gun. In

general, however, it will be sufficient if the end of the gun be pressed up against the usual rubber scalp pad.

With the method of hair waving according to the present invention, the tress of hair is steamed out very much more quickly than with the previously proposed methods of waving hair, since the Mumetal or like curler or similar element may be heated up very rapidly. In fact it is a matter of seconds only before the steaming out process is complete. Now it will be obvious that this advantage brings with it a corresponding disadvantage since, if the current be left on even for a short time after the steaming out process is complete, the Mumetal or like curler Will continue to rise in temperature and will rapidly burn the hair. It is preferable, therefore, in carrying out the present invention to provide means for interrupting the current supply immediately the desired steaming out or cooking process is completed. It is also desirable to provide a protective system which will automatically cut off the current in the event of any fault occurring in the apparatus.

Now it is known that the current flowing in a tunable oscillatory circuit coupled to an oscillator will depend upon the amount by which the tunable oscillatory circuit is out of tune with the oscillator. The graph of this function is not, however, a straight line since the current flowing in the oscillatory circuit will increase rapidly as the circuit is brought more and more into tune with the oscillator, assuming, of course, that the tunable circuit is not initially too far out of tune with the oscillator. Obviously, when a Mumetal or like curler is inserted into the field of the work coil (or when the barrel of the gun carrying the work coil is placed about the curler), the tuning of the oscillatory circuit which is coupled to the oscillator and which includes the work coil will be altered. I have found that the reactance of a mass of Mumetal, for example, the curler and/or outer sheath, varies with the temperature of the metal so that assuming the oscillatory circuit including the work coil is initially somewhat out of tune with the oscillator, the oscillatory circuit will pull more and more into tune as the Mumetal heats up. By suitably tuning the oscillatory circuit, therefore, it is possible to ensure that, when the curler (and hence the tress of hair) reaches a predetermined temperature, the oscillatory circuit will gradually pull into tune and there will be the sharp rise in high frequency current above referred to flowing in the oscillatory circuit. There will, of course, be a corresponding rise in the input current and the anode current of the oscillator and any of these may be employed to switch off the current, as explained more fully hereinafter. We have thus what is effectively a thermostatic control since the cut-out will operate when the Mumetal reaches the predetermined temperature whatever be its temperature when the gun is first placed about the same. With Mumetal it has been found to be a simple matter to set the cutout to operate when the tress of hair reaches approximately 210-220 F. and thus all chance of the hair being burnt is avoided. It must be clearly understood that, whilst Mumetal has been found to be the most satisfactory metal for the purpose in question, other metals may be employed without departing from the scope of the present invention.

In one embodiment of the present invention illustrated in Figure 8, the input current from the A. C. mains Hill is adapted to charge up a condenser H3! through a rectifier 102 and a resistance I93 which may, if desired, be adjustable, as shown. When the switch Ma on the gun is closed to complete the circuit of the Work coil, this condenser I0! is discharged through one winding 104 of a relay H14, I535, the contacts I06 of which close to complete the circuit of a relay Hl'l through a thermal delay switch H18. This relay has one pair of contacts I 99 adapted to close the input circuit of a transformer M0 for supplying H. T. to the oscillator (not shown) and a second pair of contacts I l I controlling the circuit of a pilot or indicator lamp H2. Further contacts H3 on the relay I04, I are also adapted to close to short circuit the switch 104a on the gun, the first winding lll l of the relay thus being connected across the mains in series with the above-mentioned resistance )3 and in parallel with the condenser NH. The value of the resistance I93 is such that it allows sufficient current to flow through the relay to hold the contacts Hi6 and H3 closed. The oscillator now oscillates and the hair on the curler is cooked. Included in one of the leads from the mains I00 to the rectifier N32 is the primary H4 of a current transformer I I4, I I5. The secondary H5 of this transformer is adapted to charge up through a rectifier I iii a further condenser H7 in parallel with which is a gas discharge tube H8 and the second winding H35 of the relay I04, I 05, this winding $05 being connected up in opposition to the first Winding I04. The lead from the rectifier I I6 is taken through an adjustable resistance ll9 to an adjustable point on a potentiometer I20 shunted across the condenser. The purpose of these adjustable resistances will be described hereinafter.

Now, as above explained, when the Mumetal curler or the like approaches the predetermined temperature, the current in the work circuit increases and also the current in the input circuit. Consequently, the voltage across the secondary circuit H5 of the current transformer H4, H5 increases and, by adjusting the resistances H9 and l2ll,it can be ensured that when .the Mumetal reaches the desired temperaturexthe second condenser ll! reachesa sufiicientpotential to strike the gas discharge tube .118. Current flows throughthe second winding l'05:of-the relay NM, 105, this current being in opposition to the currentin the firstwinding NM. The relay thereupon cuts out. and the contacts I06 and! 13 open. The supply circuit to the oscillator is broken and further heatingrof the Mumetal is avoided.

if desired, a second condenser gas-discharge tube assembly l2l, I22 maybe :arranged to'be charged from the secondary H .of the current transformer, this assembly including a relay I23, thedouble contacts 124 of which are included one in-each of the mains leads. The gas-discharge tube I22 of this assembly would be arranged by means of the potentiometer I25 to strike at a higher potential than the first gas-discharge tube H8. In general, such a second assembly is unnecessary, its sole function being to protect the apparatus 'in the event of failure of the first assembly.

Instead of being adapted to be operated by the sharp rise in current in the input circuit, the first condenser gas-discharge tube assembly may be operated by the rise inthe high frequency voltage in the work circuit, the condenser being charged up by the rectified high frequency current.

This modification is illustrated in Figure 9. The rectifier H6, condenser lll, gas-discharge tube H8 and the windin H ofthe relay I04, I05 are connected across the work coil 15. The remainder of the circuitis the same as in Figure 8 and the system functions as before.

Since the cut-out is operative when the reactance of the Mumetal has been reduced below a certain value, the system according to the present inventionhas the further advanta e that it is possible to cut off the supply at any time irrespective of the temperature of the Mumetal. For this purpose it is merely necessary to remove the gun from about the curler when the cut-out will operate to switch off the current.

I claim:

1. Apparatus for use in carrying out the waving of hair, which comprises: a plurality of curlers of a high permeability alloy in which high frequency heating currents can be induced to heat said curlers rapidly; a generator for generating high frequency currents; a high tension supply to said generator; at work coil fed from said generator, said work coil freely embracing one of said curlers having a tress of hair wound thereon to induce high frequency electromagnetic heating currents in said curlers; and switch means opcrating to automaticallyswitch off at least .the

high tension supply to said generator when said curlers reach a predetermined temperature.

12. Apparatus foruse'incarrying out the-waving of hair, which comprises: a plurality of curlers of a high permeability alloy in which high frequency heating currents can be induced to heat said curlers rapidly; a generator for generating high frequency currents; a-high tension supply to said generator; a work coil fed from said generator, said work coil freely embracing one of said curlers having a tress of hairwound thereon to induce high frequency electromagnetic heating currentsin said curlers; the reactance of said curler within said work coil being-reduced as its temperature increases, whereby there is .a rise in the high frequency current flowingin said work coil, in the input circuit and in the anode .circuit of said generator; and switch means provided in .oneof said .circuits operating to automatically switch off at least the high tension supply to the generator when the current inthe .circuit in question reaches a predetermined value.

3. Apparatus according to'claim 2, in which the high tension supply to the generator is controlled through the intermediary .of a double woundrelay, one winding of which is energized to close the relay contacts when the apparatus is switched on, and the winding of which is in opposition to the first winding, the second winding being connected in series with a gas discharge tube and a condenser which is charged :up by voltages derived from one of the circuits, the arrangement being-such that at the required time the gas discharge tube strikes and the second winding is energized to overcome the energization of the first winding and open the relay-loontacts.

GEORGE BRIGGS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,697,148 Spooner Jan. 1, 1929 1,734,536 Sorrel et a1. Nov. 5, 1929 1,892,106 Jancke Dec. '27, '1932 1,993,876 Davis Mar. '12, 1935 2,009,973 Nelson July 30, 1935 2,118,594 Douden May 24, 1938 2,137,189 Whitman Nov- 15, 1938 2,177,881 Durham et al 'Oct..31, 1989 2,184,534 Smith et al Dec. 6, 1939 2,284,863 Gulliksen June 2, 1942 

